Note: Descriptions are shown in the official language in which they were submitted.
CA 02278803 1999-07-28
-1-
Flat filter element and filter module composed of filter elements
Specification
The invention relates to a flat filter element, especially a
filter disk, of deep-bed filter material with a outside contour
and with flow surfaces for the filtered material and unfiltered
material. The invention relates to a filter module which is
composed of these filter elements.
Sheet filters and filter beds consist of deep-bed filter
materials which are defined as those materials which are porous
and through which flow can take place, i.e. in which convective
transport of substances through the materials is possible. Deep-
bed material can have organic and/or inorganic, fibrous and/or
grainy substances. Raw materials for the deep-bed filter
material can be for example cellulose, plastic fibers,
kieselguhr, perlites or metal oxides. Here kieselguhrs and
perlites can be added to the filter beds to increase the internal
surface and thus the prefilt volume. Furthermore, in the
cavities components of the fluid to be treated can be retained by
blocking action and/or absorption/adsorption. Examples of
materials which can be used for deep-bed filter needs include
paper, cardboard, filter beds, membranes, porous ceramic
materials, metal or polymer fabric, nonwovens, and sintered
materials, for example, of metals, metal oxides, glass or
polymers.
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_2_
The area of application of filter beds extends from
clarification and treatment of liquids in the overall beverage
industry to the pharmacy industry and the chemical industry.
Filter beds have not only a screening action with which coarse
particles are retained on the surface of the filter bed, but
especially a deep filtration action for fine particles which are
retained in the cavities within the deep-bed filter material.
Depending on the type of materials used, these filter beds can
also have an adsorption action and the surface can be post-
treated for certain applications so that no fibrous particles can
detach in the dry and wet state. In the wet state the filter
beds are relatively soft and tend to swell. This is described
for example in Horst Gasper Handbook of Industrial Solid-Liquid
Filtration Huethig-Verlag Heidelberg 1990, pp. 239 ff.
Conventionally these filter beds are operated in so-called
sheet filter devices or filter presses by clamping between filter
plates or filter frames. A survey of this art is likewise
compiled in Horst Gasper Handbook of Industrial Solid-Liquid
filtration, pp. 166 ff.
Afterwards the filter beds are inserted individually by hand
into horizontal or vertical racks. Frames of high quality steel
or plastic provide for separation of the filter beds and form
spaces for distributing the unfiltered material and for
collecting the filtered material. Due to the extensive manual
activity in inserting the filter beds into the racks when the
filter beds are removed from the racks and due to the
subsequently necessary cleaning of the filter racks, the
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_3_
operation of these filters is connected with high personnel
costs. Cleaning is especially complex and under certain
circumstances also dangerous to the personnel when corrosive
media have been filtered. In addition, the investment costs for
these filter devices are very high, since a specially designed
filter frame is necessary for each filter bed.
Furthermore, during operation these filters generally have
low but measurable fluid losses which emerge on the faces of the
filter beds therefrom due to their open construction. Drip
losses can only be prevented by special complex measures with a
plurality of seals. One form of sealing to the environment is
given in DE 39 06 816 C3.
The disadvantage with respect to handling is balanced by the
advantage that the production of filter beds or filter nonwovens
is relatively economical because this can be done on continuously
operating machines.
Deep-bed filter modules are known in diverse designs, it
being common to most of these filter modules that the units are
produced from flat materials, therefore filter cardboard, beds,
papers, nonwoven or fabrics. EP 0 461 424 B1 discloses a deep-bed
filter which has a pleated filter bed to increase the filter
surface. Flow through a pleated filter bed takes place
perpendicularly to its surface.
A similar arrangement is also described in EP 0 475 708 A1.
Other known embodiments relate to deep-bed filter material which
is wound around an inner core into one or more beds, and to
increase the filter surface the filter medium can also be wound
CA 02278803 1999-07-28
-4-.
around the inner core in.a loop. In these embodiments as well
the filter media flow through essentially perpendicular to the
surface of the filter bed.
A filter module of sheet filter elements stacked on top of
one another is disclosed in EP 0 291 883 A3. To produce the
described module, first of all filter pockets with internal
drainage material are produced and they are surrounded by a
sealing element and a plastic mass. These pockets are then
stacked on top of one another. In this filter module additional
components are also necessary for the spaced arrangement of the
filter beds. Flow through the filter module takes place in the
plane of the filter beds through which flow must take place
perpendicularly to the plane of the bed in order to effect
filtration.
WO 94/09880 describes a filter element for deep-bed
filtration which consists of a porous, thick-walled, self-
supporting tubular filter element with a hollow core. This
tubular filter element consists essentially of two shells, the
outer shell having large pores and the inner shell having fine
pores. One advantage is that in this structure, in contrast to
the fine-pore filter modules with a homogenous structure, if they
are produced in the known manner, they do not offer such high
resistance to the liquid. On the other hand the filtration
surface is small.
The object of the invention is to devise a flat filter
element, especially a filter disk, and a filter module which is
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-5 -
composed of these filter elements, which enables simple handling
and disposal for a large filtration surface.
This object is achieved with a flat filter element by its
having an inner structure which is formed by at least one
opening, the boundary surface of the opening which is formed by
the deep-bed filter material forming a flow surface and by the
flow surface being located essentially perpendicularly to the
plane of the filter element.
The deep-bed filter module is composed of at least two such
filter elements, these filter elements being stacked on top of
one another such that only the openings of the same type are
connected to one another and in this way form filtered material
and unfiltered material channels.
Advantageous embodiments are described in the dependent
patent claims.
The invention is based on the finding that filter disks of
deep-bed filter material without intermediate plates and the like
can be used when flow takes place through the filter element, not
perpendicularly to the plane of the disks, but radially, i.e. for
example via the peripheral surface. Since the filtration surface
in this mode of operation is low, developments in this direction
have not been pursued in the past. But it has been surprisingly
found that this defect can be eliminated by the formation of an
inner structure, because other surfaces are exposed by providing
openings which can be used as the flow surface for the filtered
material or unfiltered material.
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One advantage of the invention consists in that on the basis
of the freely selectable geometry of the inner structure the
magnitude of the filtration depth and the size of the filtration
surface, i.e. the flow surface, can be freely set independently
of one another. In this way several possibilities open up for
the structure of the deep-bed filter material. In open-pore
deep-bed filter material a large filtration depth, i.e. a greater
distance between the openings, makes it possible to adjust the
same separation rate and thus separation efficiency as in a
material which has smaller pores and low filtration depth.
Furthermore, the adsorptive properties of the deep-bed
filter material can be better used because the filtration depth,
i.e. the actual filtering area of the deep-bed filter material,
is no longer limited, as in the prior art.
Since in the filter module as claimed in the invention the
holding frames which have been conventional in the prior art are
eliminated, the adsorption capacity is increased, i.e. more
exchanger material can be accommodated in a filter module per
enclosed space.
In particular, activated charcoal, PVP, PVPP and ion
exchanger materials as well as selectively acting adsorbents and
active media can be used as additives with adsorption properties.
Another advantage arises in the area of disposability of the
filter modules. Because intermediate plates or holding frames of
another material are not used, the filter module can be disposed
of as a whole without the need to separate the filter disks of
other materials. In this respect especially filter elements of
CA 02278803 1999-07-28
100% organic materials, so-called biobeds, are advantageous,
since they can be for example completely thermally processed.
The openings in the filter elements can be formed during
production of the filter beds by using the corresponding shaped
inserts. Another possibility is to make the openings after
producing the filter element; this can be done in the
conventional manner, for example by punching or water jet
cutting. The material removed from the filter element can be
returned to the process of producing additional filter elements.
In this respect no waste is formed.
The alignment of the flow surfaces depends on the production
process. Thus, during punch-out also inclined flow surfaces can
be produced which are not aligned perpendicularly to the plane of
the filter element and which are somewhat sloped; in a disk this
is the disk plane, deviations from a right angle by a maximum ~
10° being possible. One of the flow surfaces which is not
located within the filter element can also be the face of the
filter element, i.e. the peripheral surface in a filter disk.
Preferably the sum of all flow surfaces of a filter element,
which is also to be understood as both the outer flow surface and
also the flow surface located within the filter element, is
larger than the sum of the outer peripheral surface of an
extremely small convex body which jackets the filter element and
the outer peripheral surface of an extremely large convex body
which is inscribed into any opening of the filter element.
Convex bodies are for example spheres, ellipsoids, cylinders,
cones, angles, tetrahedrons or cuboids and are described in the
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_g _
small Mathematical Encyclopedia, VEB Bibliographisches Institut,
Leipzig 1979, p. 625.
Advantageously the filter element has an outside contour
which is matched to the inner structure so that the width of the
effective filtration area of the deep-bed filter material is the
same everywhere. This ensures that the filtration action of the
filter element is the same everywhere along its entire periphery.
Hut it can also be a good idea to make the width of the effective
filtration area in the outer area larger than in the interior of
the filter element in order to increase the stability for example
and optionally to hold fixing structures.
To achieve a large filtration surface, preferably a type of
finger-shaped opening is chosen for the opening. Matching the
outside contour to the inner structure of the filter element
yields a meandering configuration with a large peripheral surface
and thus a correspondingly large boundary surface of the opening.
One such flat filter element can for example be exposed to flow
from the outside, the unfiltered material having to penetrate an
equally thick effective filtration area of the deep-bed filter
material everywhere along the periphery. The filtered material
collects in this case within the opening and is discharged from
there via corresponding accessory parts.
Preferably there will be at least two openings which are not
connected to one another and which are used as the filtered
material and unfiltered material channel. These openings are
located next to one another such that the width of the effective
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filtration area of the deep-bed filter material located in
between is the same everywhere.
The thickness of the filter beds can also be chosen to be
different. The thicker the filter elements or the filter disks,
the fewer elements are needed to build a filter module. Also the
cost for producing the openings relative to the volume of deep-
bed filter material is reduced.
The effective filtration areas are preferably >_ 5 mm,
especially 8 to 20 mm thick. The effective filtration area can
thus be less than or equal to or even larger than the thickness
of the filter element. Effective filtration areas 2 mm thick
with a width of the openings of 0.5 mm are also conceivable. The
filtration action can be influenced by the arrangement of the
openings in this way.
In the extremely fine clarification area it is not necessary
for the openings to have large dimensions because loading with
particles is extremely low, so that no clogging of the filtered
material or unfiltered material channels formed by the openings
can occur. Therefore it is sufficient when simply slits are made
in the filter element or the filter disk as openings. The slits
can run both in the radial direction and also in the peripheral
direction and can also be combined at will with wider openings.
These slits can be made with a knife, the deep=bed filtration
material simply being displaced; this has the advantage that no
material is formed, for example as in punching out, which must be
returned to the production process.
CA 02278803 1999-07-28
_10_
To enable delivery of unfiltered material into the interior
of the filter element and the removal of filtered material from
the filter element, there is at least one opening (opening of the
first type) which extends as far as the edge of the filter
element or which is connected to the edge via at least one
connection opening. The openings of the first type can be used
for supply of unfiltered material, but also in the reverse mode
of operation for removal of the filtered material.
These openings of the first type can be combined with at
least one ogening (opening of the second type) which is not
connected to an opening of the first type and which discharges in
at least one collection opening or is connected via at least one
connection opening to the collection opening. In contrast to the
meandering structure of the filter element several openings
enable filtration in almost all areas within the filter element.
Openings which extend as far as the edge of the filter
element can be abandoned when the feed or discharge of unfiltered
material or filtered material into/out of the interior of the
filter element is ensured by the appropriately formed end plates.
A filter disk with a round outside contour is preferred, the
openings of the first and second type lying on concentric
circles. The openings of the first type are connected to the
edge of the disk via a connection opening which extends in the
radial direction. A collection opening can be located in the
center of the disk which is connected via a radial connection
opening to the openings of the second type.
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~ -11-
To form a filtration surface as large as possible, the
openings of the first type and second type are arranged in
alternation. Preferably all the available surfaces of the filter
elements is provided with openings. The width of the openings
must be matched to the respective filtration task. Small widths
make it possible to provide as many openings as possible on a
filter element and thus to make available a large filtration
surface. On the other hand, if not working in the extremely fine
clarification area, the dimensions of the openings should not be
selected to be so small that blocking takes place within an
extremely short time within the openings so that the filter
element must be replaced.
The filter disk can have not only a round or oval outside
contour, but also an outside contour with n corners, the openings
being arranged preferably parallel to one edge of the disk.
If the filter disk has preferably a round outside contour,
the openings of the first type and the openings of the second
type can also lie on at least one spiral. The spirals are
intertwined into one another in this case so that within the
individual turns of the spirals filtration can take place by
effective filtration areas which are largely of the same
thickness.
To achieve a filtration surface as large as possible within
the filter element, preferably elongated openings which are as
narrow as possible are made in the filter element. The inner
structure thus becomes screen-like or grid-like, the stability of
the filter element being determined only by the remaining deep-
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. . _12_
bed filter material between the openings of the first and second
type. To increase stability, the openings and/or the connection
openings preferably have stiffening bridges. These stiffening
bridges consist preferably of the same material as the filter
element, can have the same thickness as the filter element, or
can also be made thinner. When the openings are punched out the
stiffening bridges can be embossed or compacted at the same time
so that the thickness is less than the thickness of the filter
a lement .
When the stiffening bridges within the openings have the
same thickness as the filter element, when the filter disks are
stacked on top of one another for example the filtered material
cannot reach the collection opening from all openings, so that
end plates of the filter module which are made accordingly would
be necessary to combine the filtered material and unfiltered
material flows. To establish connections between openings of the
same type, the filter elements are turned, shifted or similarly
stacked on top of one another depending on the configuration of
the openings and stiffening bridges.
To guarantee the alignment of the individual filter elements
when stacked on top of one another in the indicated manner, the
edge can have at least one fixing recess; this facilitates work
when the filter elements are stacked on top of one another.
There can also be fixing recesses within the filter element. An
irregular inside or outside contour also enables fixing and
assignment of the filter elements in conjunction with suitable
components.
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Identical or different types of filter elements can be
stacked on top of one another to form a filter module. In the
simplest case the types of filter elements or disks are simply
mirror-symmetrical.
Filter elements with openings which are connected to the
edge of the filter element can be combined with filter elements
with openings which are not connected to the edge of the filter
element. Preferably these filter elements are then stacked
alternately on top of one another. Depending on the
configuration of the bridges and arrangement of the openings the
filter elements must be stacked on top of one another, turned
against one another, so that the pertinent openings in the filter
module form channels for filtered material and unfiltered
material. The turning angle can also be determined by the
location and width of the stiffening bridges, or a fixed angle of
rotation, for example, 180°, is stipulated.
The filter elements can be placed directly on top of one
another, but they can also be cemented or bonded. It is also
conceivable to place between two filter elements an intermediate
layer with or without openings, for example of nonskid material
in order to improve the stability of the filter module; this is
especially important when backflushing of the filter module is to
be done.. For example a corresponding film or also conventional
filter disks without openings and without an inner structure are
suited for this purpose.
The filter module has two end plates between which the
filter elements are located, especially one end plate being
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supported to move as a result of the swelling capacity of the
filter beds.
Sample embodiments are explained below using the drawings.
Figure la shows an overhead view of a meander-shaped filter
element,
Figure ib shows a perspective view of the filter element
shown in Figure la,
Figure 2 shows an overhead view of a filter element
according to another embodiment,
Figure 3 shows a section through the filter elements shown
in Figure 2 along line III-III,
Figures 4 to 9 show overhead views of filter elements of
different embodiments,
Figure 10 shows an extract of a filter element with slots,
Figure 11 shows a perspective view of a filter module,
Figure 12 shows a filter module in an exploded view,
Figure 13 shows an enlarged detailed view of an extract of
two filter elements stacked on top of one another, and
Figure 14 shows a filter device with a filter module.
Figure la shows a flat filter element 10 which has a
meander-shaped structure. After producing a conventional filter
element, for example with a quadratic shape, an opening 20 is
made in the filter element 10, by which the inner structure 17 is
established. The surface of the opening 20 which is bordered by
the deep-bed filter material 12 forms a flow surface ila or 11b
for the filtered material and unfiltered material which is
roughly twice as large as the corresponding surface in a ring
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-15-
with the same area. In the embodiment shown here it is a finger-
like opening 20 to which the outside contour 18 is likewise
adapted for example by punching out. The remaining deep-bed
filter material 12 thus has a meander-like structure, the width
of the effective filtration areas being the same everywhere.
If this filter element 10 is exposed to flow radially for
example from the outside via the peripheral surface 19, loops on
the outside form unfiltered material spaces 25. Within the
filter element 10 the filtered material collects and is removed
through a core hole 34 which is shown by the broken line in an
end plate which is not shown.
This filter element 10 can also be exposed to flow in the
reverse direction by delivering the unfiltered material via the
core hole 34 and thus via the opening 20. In both cases the
filter element 10 is exposed to flow parallel to the plane of the
filter element, therefore essentially radially.
Figure ib shows in perspecti~ the filter element 10 which
,: ..
is shown in Figure la to illustrate the convex bodies 60, 62.
The filter element-10 is jacketed by the smallest possible convex
body (outside body) which in the embodiment shown is a polyhedron
with an octagonal base surface, the edges being rounded. The
pertinent outside peripheral surface 61 can be imagined as a band
placed around the filter element 10. Similarly, a convex body as
large as possible (inside body) 62 is inserted into the opening
20 and has a peripheral surface 63. This convex inner body has a
rectangular base surface. As a result of the polygonal
configuration of the filter element 10 the sum of the flow
CA 02278803 1999-07-28
' -16-
surfaces ila, 19 is larger than the sum of the surfaces 61 and
63.
Figure 2 shows another embodiment of a filter element in the
form of a disk 10' in which two concentric annular openings 20
and 30 are made in the filter disk 10'. Neither opening 20, 30
is connected to one another and they form one opening of the
first type and one opening of the second type. The outside
peripheral surface 61 of the convex outside body 60 is identical
to the outside peripheral surface 19 of the filter disk 10'.
The openings 20 and 30 are not completely closed into a ring
here because in addition there are connection openings 21 and 31
which intersect the respective circles of the openings 20 and 30.
The connection opening 21 establishes the connection from the
inner opening 20 to the peripheral surface 19. The connection
opening 31 extends likewise in the radial direction and joins the
outer annular opening 30 to a round hole in the middle which
represents a so-called collection opening 33. All openings
together form the inner structure 17.
The collection- opening 33 in the embodiment shown here
represents the largest opening within the filter disk 10' so that
the largest possible convex inside body 62 (shown by cross
hatching) which is identical to the collection opening 33 can be
inserted. If the sum of all flow surfaces is compared to the sum
of surface 61 and'surface 63, this sum of all flow surfaces is
larger.
The width of the effective filtration areas between the
peripheral surface 19 and the outer opening 30 or the outer
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' -17-
opening 30 and the inner opening 20 and between this opening 20
and the collection opening 33 is the same everywhere so that the
same filtration action is achieved everywhere in the filter disk
10~.
The disk can be operated such that the unfiltered material
is supplied to the inner opening 20 via the input of the
connection opening 21 labelled 24. The ffilter element is thus
exposed to flow not only via the peripheral surface 19, but also
in the interior via the flow surfaces which are formed by the
inner opening 20.
As can be seen in Figure 3 which shows a section along the
line III-III through the filter element as shown in Figure 2, in
the direction of the arrow 13 the unfiltered material penetrates
the effective filtration areas from the outside, i.e. via the
peripheral surface 19 which thus forms a flow surface. The
filtered material f lows on the flow surfaces lib into the
corresponding opening 30 where the ffiltered material is collected
and reaches the collection opening 33 via the connection opening
31. At the same time via the connection opening 21 which is
shown only in Figure 2 unfiltered material is supplied to the
opening 20, where the unfiltered material penetrates through the
flow surfaces ila into the deep bed filter material. As the
filtered material it then passes through the flow surfaces iib
into the opening 30 and into the collection opening 33.
In the reverse mode of operation the unfiltered material
would be delivered via the collection openings 33 from where is
would reach the openings 30 via the connection opening 31 where
CA 02278803 1999-07-28
_18.
it is distributed and would emerge through the effective
filtration areas as filtered material in the inner opening 20.
The filtered material would be discharged then in this case via
the connection opening 21.
Figure 4 shows another embodiment which corresponds
essentially to the one shown in Figure 2. The entire filter disk
s
10' under certain circumstances can become too unstable due to
the annular openings 20 and 30, especially when the diameter is
very large and the thickness of the filter elements is very low.
To increase stability, in the opening 20 there are two
stiffening bridges 41 which divide the opening 20 into three
roughly equal-sized, arc-shaped sections. Accordingly the
outside opening 30 has two stiffening bridges 42. When the
filter disks 10' are stacked on top of one another to form a
filter module 1, as is shown in Figure 11, in the embodiment
shown in Figure 4 it must be watched that the disks are exactly
aligned to one another so that the connection openings 21 and 31
do not accidently cross one of the openings 20 or 30; this would
lead to mixing of the filtered material and unfiltered material.
Therefore it must be watched during assembly that the openings of
the first type, here the opening 20, 21, cannot connect to the
openings of the second type (openings 30, 31, 33). To fix the
alignment of the filter disk 10' on the peripheral surface 19
there are fixing structures 44 into which the rods 71 shown in
Figure il f it. In Figure il the filter disks l0' shown in Figure
4 are combined with filter elements as shown in another
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-19-
embodiment, with openings which are not connected to the outer
edge.
When identical filter disks 10~ as shown in the embodiment
in Figure 4 are stacked on top of one another, the connection
openings 21 all lying on top of one another, it is necessary to
provide a corresponding end plate so that the individual sections
of the openings 20 and 30 can communicate with one another. So
that a complex end plate is not necessary, the filter disks l0
can also be stacked on top of one another twisted somewhat to one
another. The angle of twist must be chosen according to the
width of the stiffening bridges 41 and 42 such that the openings
20 and 30 of the adjacent filter disk 10~ cover these stiffening
bridges. On the other hand, the twist should not be chosen to be
so great that the connection openings 21 and 31 cross the
openings 20 and 30.
Figure 5 shows another embodiment in which there are a total
of six concentric annular openings. The openings 20a to c form
the openings of the first type, while openings 30a to c form the
openings of the second type which are connected via the common
connection opening 31 to the collection opening 33. Accordingly
the openings 20a to c are connected via the connection opening 21
to the peripheral surface 19. This embodiment also has
stiffening bridges 41 and 42.
The following table lists the flow surface in square meters
for a filter module consisting of 250 filter elements with a
thickness of 0.4 cm. As the number N of annular openings
increases, with a correspondingly larger outside diameter d max
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-20-
of the filter elements at N = 15 openings almost 70 m2 are
reached, the width of the openings is 5 mm and the width of the
effective filtration areas is 20 mm.
N d max [mm] A Filtered material [m2]
0 60 0.17
1 160 0.82
2 260 2.04
3 360 3.82
4 460 6.16
560 9,Og
6 660 12.55
7 760 16.60
8 860 21.21
9 960 26.38
1060 32.12
11 1160 38.43
12 1260 45.30
13 1360 52.73
14 1460 60.73
1560 69.30
The quotient of the filter surface multiplied by the filter
thickness and the space occupied by the filter module is of
interest since this value reproduces the holding capacity of the
filter module relative to the space. Considering that in
conventional bed filtration there are filter frames 1 mm thick
between the beds, this quotient is 29%. Conversely, in the
module as claimed in the invention (for example for N = 12) this
quotient is 73%. Thus the modules as claimed in the invention
have much better space use.
Figure 6 shows another embodiment in which there a two
openings 20 and 30 in the form of intertwined spirals. These
openings 20 and 30 have stiffening bridges 41 and 42.
Figures 7 to 9 show filter disks 10' which are provided with
straight openings 20a to f, 30a to g. All openings of the first
CA 02278803 1999-07-28
-z~-
type 20a to 20f discharge on the peripheral surface 19. All
openings of the second type 30a to 30g are connected via two
radial connection openings 31a and 31b to the collection opening
33.
Figure 8 shows a similar embodiment, but with a quadratic
outside contour. The openings 20, 30 run parallel to the side
edge 16 of the filter element 10. In addition, there are two
collection openings 33a and b. Within the openings of the second
type 30a to c and 30d to f thus two groups are formed again. In
this embodient there are stiffening bridges 41 and.42 which
divide the respective openings 20a to 20 f and 30a to f into
sections of differing length.
Figure 9 shows an octagonal filter disk 10' in which both
the openings 20a-f a, 30a-g and also the connection openings 21a,
b, and 31a, b are provided with stiffening bridges 41, 42 and 43.
To form a filter module identical filter disks 10' can be stacked
on top of one another. There are various possibilities for this.
Thus adjacent disks can be arranged turned 180° each. This is
ensured by the respective connection bridges 41, 42 and 43 coming
to rest over a corresponding opening so that only the openings of
the same type are connected to one another and no mixing of the
filtered material and unfiltered material can occur. Turning
only each n-th element by 180° is also conceivable.
Figure 10 shows another embodiment of a filter element 10 in
which wide openings 20, 30 are combined with slots 27, 37 which
are connected to the respective slots. It is also possible to
provide exclusively slots 27 and 37.
CA 02278803 1999-07-28
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Figure 11 shows a filter module 1 which for example has nine
filter disks, of which the filter disk 10' corresponds to the
embodiment shown in Figure 4. The filter elements are placed on
an end plate 70 on which two rods 71 are attached which fit into
the corresponding fixing recesses 44 on the disk edge and in this
way guarantee the alignment of the filter disks 10'. On the rods
71 the entire module can be grasped and removed from the
filtration device. Complicated installation and removal are
eliminated. Furthermore the entire module except for rods 71 and
the end plate 70 can be disposed of as a whole without the
individual disks having to be separated from one another.
Figure 12 shows a stack of filter disks in an exploded view,
two embodiments of filter disks l0a' and 10b' being placed on top
of~one another in alternation. The filter disks l0a' have a
radial connection opening 21 with one entry 24 on the edge, while
filter disks lOb' have exclusively concentric openings 20, 30. A
corresponding arrangement of stiffening bxidges within the
openings ensures that the openings of the first type do not cross
the openings of the-second type. The collection openings 33 on
top of one another form a channel 35 for the filtered material
which is shown by the broken line, while the space 36 for the
unfiltered material forms the space which surrounds the filter
elements l0a', b'.
Figure 13 shows an enlarged extract of two disks placed on
top of one another. The unfiltered material is supplied through
the connection opening 21b and is distributed into the openings
20b. It can be clearly seen that the stiffening bridges 41a, 42a
CA 02278803 1999-07-28
-23-
of the top disk l0a' are above the corresponding openings of the
lower disk lOb'. Accordingly the stiffening bridges 41b and 42b
are located in the area of the corresponding openings 20a and 30
of the upper disk l0a'. The flows 13 of unfiltered material 13
and flows 14 of filtered material are routed in the manner of
waves by overflows and underflows of the stiffening bridges 41b
and 42b into the respective holes. The collected filtered
material is removed via the connection opening 31b.
Not all the stiffening bridges 41a, 42a, 41b, 42b need have
the same~thickness as the filter disk l0a', lOb'. For purposes
of illustration therefore the stiffening bridge 41a' is shown
with a reduced thickness.
Figure 14 illustrates a filtration means 51 into which a
filter module 1 composed of a plurality of filter disks 10' is
installed. The filter module stands on a bottom solid end plate
53. To compensate for changes in the location of the module for
operation, the upper end plate 52 is movably supported. In the
case shown the space 25 for the unfiltered material is located
outside of and above the module 1. The filtered material space
here is located within and underneath the module 1. The
unfiltered material passes through the connection 54 in the side
wall of the container jacket 56 into the filtration means 51 and
the filtered material leaves it through a central connection 55
on the bottom thereof.
